/*
 * StreamProvider.java January 2010
 *
 * Copyright (C) 2010, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.stream;

import java.io.InputStream;
import java.io.Reader;

import wx.xml.stax.api.stream.XMLEventReader;
import wx.xml.stax.api.stream.XMLInputFactory;

/**
 * The <code>StreamProvider</code> object is used to provide event
 * reader implementations for StAX. Wrapping the mechanics of the
 * StAX framework within a <code>Provider</code> ensures that it can
 * be plugged in without any dependencies. This allows other parsers
 * to be swapped in should there be such a requirement.
 *
 * @author Niall Gallagher
 * @see wx.xml.simpleframework.xml.stream.StreamProvider
 */
class StreamProvider implements Provider {

    /**
     * This is the factory that is used to create StAX parsers.
     */
    private final XMLInputFactory factory;

    /**
     * Constructor for the <code>StreamProvider</code> object. This
     * is used to instantiate a parser factory that will be used to
     * create parsers when requested. Instantiating the factory up
     * front also checks that the framework is fully supported.
     */
    public StreamProvider() {
        this.factory = XMLInputFactory.newInstance();
    }

    /**
     * This provides an <code>EventReader</code> that will read from
     * the specified input stream. When reading from an input stream
     * the character encoding should be taken from the XML prolog or
     * it should default to the UTF-8 character encoding.
     *
     * @param source this is the stream to read the document with
     * @return this is used to return the event reader implementation
     */
    public EventReader provide(InputStream source) throws Exception {
        return provide(factory.createXMLEventReader(source));
    }

    /**
     * This provides an <code>EventReader</code> that will read from
     * the specified reader. When reading from a reader the character
     * encoding should be the same as the source XML document.
     *
     * @param source this is the reader to read the document with
     * @return this is used to return the event reader implementation
     */
    public EventReader provide(Reader source) throws Exception {
        return provide(factory.createXMLEventReader(source));
    }

    /**
     * This provides an <code>EventReader</code> that will read from
     * the specified reader. The returned event reader is basically
     * a wrapper for the provided StAX implementation.
     *
     * @param source this is the reader to read the document with
     * @return this is used to return the event reader implementation
     */
    private EventReader provide(XMLEventReader source) throws Exception {
        return new StreamReader(source);
    }
}